Mnuchin's comments confirm the fears of many analysts, who assumed that the timeline for tax reform would be pushed back after the GOP's failure to pass the American Health Care Act. House Speaker Paul Ryan and President Trump admitted that not repealing Obamacare's taxes (which the AHCA would have done) makes tax reform more difficult.

Trump promised during the campaign to cut the federal corporate tax rate to 15% from its current 35% and lower personal taxes. He heralded the cut as the biggest since Ronald Reagan's presidency.